Container sealing roof structure

ABSTRACT

A container for liquefied gas has a domed cover sealed to the top edge of the sides of the container. The cover is supported on a lattice of beams. A horizontal tray covering the opening in the top of the container is suspended from the beam-lattice and is filled with water frozen to ice by the liquefied gas. A band sealed to the top edge of the sides of the container around the tray has its upper edge turned over into the ice in the tray to form an inner seal between the inside of the container and the domed cover.

United States Patent Hamilton [451 Mar. 28, 1972 [541 CONTAINER SEALING ROOF 3,249,251 5/1966 Nachsen ..e1/.s x STRUCTURE 3,326,011 6/1967 Sparling ..6l/.5 X 3,352,443 11/1967 Sattelberg et al. ...220/l8 X Inventor; William Hamilton, Mill Brae, 01d Gulld- 3,359,739 12/1967 Bishop ..61/.5 f r R Camberley, England 3,360,941 1/1968 Jackson .,6l/.5

[22] Filed: 1969 Primary Examiner-Jacob Shapiro [2|] Appl. No.: 791,989 Attamey-Woo'dhams, Blanchard and Flynn T T [30] Foreign Application Priority Data [57] ABS RAC A container for liquefied gas has a domed cover sealed to the June 26, 1968 Great Bntaln ..4,299/68 mp edge of the sides of the container. The cover is Supported on a lattice of beams. A horizontal tray covering the opening [52] US. Cl ..6l/.5, 62/45, 220/9, in the top of the container is Suspended from the 220/131 220/18 ttice and is filled with water frozen to ice by the liquefied gas. Int- Cl ..B65g A band ealed to the top edge of the ides of the container of Search 13, around the tray has its upper edge turned over into {he ice in 220/9 the tray to form an inner seal between the inside of the container and the domed cover. [56] References Cited 10 Claims, 7 Drawing Figures UNITED STATES PATENTS 3,205,665 9/1965 Van Horn ..6l/.5

PATENTEDMms 1912 3. 651 ,648

SHEET 1 OF 4 Lu/W HAMILTON PATENTEDHARZB 1972 SHEET 2 UP 4 1 CONTAINER SEALING ROOF STRUCTURE The present invention relates to an improved sealing roof structure for containers and more particularly though not exclusively for containers for liquefied gases, for example natural fuel gases.

Such a container may be, for example, a large circular cavity excavated in the ground, the soil around the cavity being frozen through an appropriate thickness and maintained frozen at least for the main part by the low temperature of the liquefied gas. The usually dome-shaped roof or cover of the container may be supported at its edge on the ground around the opening to the cavity.

Alternatively the container may be partly or entirely above the ground. In this case the side of the container may be a stfucture formed of or including impervious and heat-insulating materials, with the cover of the container being supported at its edge upon the upper edge of the side of the container.

According to the present invention there is provided a container and a closure for the upper end thereof, said closure including an external part, and an internal part having the general form of a receptacle for containing liquid which can be frozen solid to form a solid barrier layer between the interior of the container and the external part of the closure.

In an embodiment of the invention the receptacle has the general form of a tray.

The internal part of the closure may include a peripheral member formed of gas-impervious sheet material shaped to a cross-sectional form of general U-shape with the inner limb of the U extending downwards into the tray and the outer limb of the U extending below the base of the tray and in contact with a surface of the side wall of the container so that a gas-tight seal is provided between the interior of the container and the upper side of the tray.

In a preferred embodiment, the external part of the closure comprises a gas-impervious cover carried by a frame structure supported at the upper end of the side of the container, and the receptacle is mounted in suspension from the frame structure. v

The outer peripheral portion of the external part of the closure may extend outwards beyond the external surface of the aperture in the upper end of the container and a further sheet of gas impervious material may be disposed around the external surface of the periphery of the aperture. The further sheet may be shaped for engagement with the external surface and to extend across the gap between the external surface and the outwardly extending external part of the closure whereby a gas-tight seal is provided against the entry of gas into the space between the external and internal parts of the closure.

The lower edge of the outer limb of the sheet of U-form and the part of the further sheet engaged with the external surface of the periphery of the aperture may be located in a space in the wall of the container containing a liquid capable of freezing solid when subjected to the temperature of the liquid to be stored in the container to provide a gas-tight seal preventing access of gas to the space between the external and internal parts of the closure.

The liquid to be frozen in the tray may be water, and the liquid to be frozen in the space in the wall of the container may be water or a mixture of sand and water.

In the preferred arrangement, the gas-tight enclosure between the cover of the container and the tray is filled with inert gas, for example, nitrogen, at slightly greater than atmospheric pressure so that the entry of air into the enclosure with consequent risk of explosion where inflammable gas is present is avoided, and at the same time entry of moisture from the exterior into the enclosure with consequent possible undesirable increase in the quantity of frozen material in the tray at the underside of the enclosure is prevented.

A presently preferred embodiment of the invention as applied to a container for liquefied natural gas will now be described, by way of example only, with reference to the accompanying drawings in which:-

FIGS. 1 and 1A show, respectively, sections on diameters of a circular cavity-in-the-ground container and a circular aboveground container,

FIG. 2 shows, in greater detail, the edge of the cavity-in-theground container of FIG. 1,

FIG. 3 shows a section through the impervious ice barrier layer of the container, and the structure supporting the layer,

FIG. 4 shows a section, in a plane perpendicular to the plane of the section of FIG. 3, of the layer and supporting structure of FIG. 3,

FIG. 5 shows in section the edge of the tray containing the impervious barrier layer, as applied to a cavity-in-the-ground container and FIG. 6 shows, in section, the edge of the above-ground container of FIG. 1A.

Referring to FIG. 1, and to FIGS. 2 to 5, a cavity 1, excavated in the ground, has a sidewall 2 of soil frozen through an appropriate thickness, e.g., 10 to 20 feet.

A flat platform 8 formed for example of corrugated or troughed aluminum floor sheeting 9 (FIG. 5) is constructed to cover the opening or aperture at the top of the cavity 1, and upon the upper surface of the platform 8 are applied sheets of waterproof material 10 such as bitumen impregnated sheeting with the peripheral edges 11 thereof upturned so that a shallow horizontal tray 12 suitable to be filled with a predetermined quantity of water is formed. Water in the tray 12 will be converted to ice by the low temperature of the cavity so that an ice barrier 13 is formed below the roof of the container. Preferably the troughs or corrugation in the metal sheeting 9 are filled with sand 14 which when frozen will increase the stability of the tray support.

The platform 8 is supported on I-beams 14A which rest freely at their ends on a hollow, peripheral and fixedly mounted annular aluminum beam 15 which is suspended from the hollow beams 17 (FIGS. 1 and 2) by suspender rods 15A. The I-beams 14A are supported at points intermediate their ends, by aluminium suspender rods 16 attached at their upper ends to the hollow beams 17 of aluminium which form a roof lattice covered with a domed cover 18. A

The roof lattice is anchored at its periphery to a mild steel hollow ring beam 19 resting upon the ground or upon a supporting ring of concrete 21 itself resting on the ground around the edge of the aperture to the cavity and the domed cover sheet 18 also rests with its outer peripheral edge upon the ring beam 19 and is welded thereto.

In the case shown in the drawings the hollow ring beam 19 rests on plates of mild steel 20 in segments. Some of the plates 20 are wedge-shaped in section and may be moved radially inwards or outwards so that the spacing of the ring beam 19 from the upper surface of the concrete ring beam 21, on which the plates 20 in this case rest, may be varied to maintain the ring beam 19 in a horizontal plane as the concrete ring beam 21 rises or falls as a result of ground heave. The concrete ring beam 21 is in segments and has gaps between the ends of the segments to allow water from ice, which may form and melt on the inner side of the beam 21, to escape. The concrete ring beam 21 rests on superimposed layers of asphalt 22 and heatinsulating material 23 on the upper edge of the frozen soil 2 comprising the sidewall of the container. A first band 24 of sheet stainless steel has its lower edge embedded in frozen sand 25 in a continuous circumferential trench or recess 26 in the upper edge of the frozen soil 2 comprising the sidewall of the container. A lip portion 27 (FIG. 5) extends inwardly from the main portion of the band 24, and from the lip portion 27 there extends a downwardly directed portion 28 extending into the tray 12 so as to be embedded in the ice barrier 13 at its edge. There is thus formed a seal preventing the passage of gas from below the ice barrier to the space 31 below the domed roof cover and above the ice barrier.

A second stainless steel band 29 spaced outwardly from the band 24, has its lower edge embedded in the frozen sand 25 in the trench 26. A flange 30 extends outwardly from near the upper edge of the band 29, the outer edge of the flange 30 being welded to the inside of the continuous mild steel ring beam 19. The flange 30 prevents access of gas from the space below the flange 30 to the gas-tight space 31 between the roof cover 18 and the ice barrier 13. The gas tight space 31 is filled with nitrogen at a pressure slightly greater than atmospheric. The space between the bands 24 and 29 is filled with heat-insulating material layers 32. The heat-insulating material layers 32 may also extend over and above the impervious ice barrier layer 13, where they are supported on a floor 33 of expanded aluminium sheeting which is in turn supported on a grid of I- beams 34 carried by the aluminium suspender rods 16. This arrangement of insulating material in conjunction with the sealing bands provides a shield against access of heat from the domed roof ofthe container to the ice barrier in the tray.

A ring of yielding elastic material 35 (FIG. supported on a bracket 36 on the inside of the band 24, spaces the main part of the band 24 from the peripheral wall of the bitumen sheeting tray 12 containing the layer of ice l3, and allows for differential contraction or expansion of the band 24 and the tray 12 containing the layer of ice 13.

The structure of the upper edge of the above-ground container shown in FIGS. 1A and 6 is identical with that of the cavity-in-the-ground container described above, except where indicated below.

The sidewall of the container comprises an inner wall 37 of gas impervious sheet material, the layer of insulating material 32, and an outer wall of concrete 38. The upper end of the inner wall 37 forms the above-mentioned inner, or first band 24. The upper edge of the inner wall 37 is turned over to form the lip portion 27 (FIGS. 5 and 6) and the downwardly directed portion 28 embedded in the ice barrier 13.

The edge of the mild steel roof 18 is welded to an anchor member (not shown) constituting an uninterrupted ring around the opening to the container. The anchor member is embedded in the concrete of a reinforced concrete ring beam 39 integral with the outer concrete wall 38.

Although the first and second metal bands described above are preferably of stainless-steel other metals may be used for example aluminium or aluminium-based alloys.

In use the weight of the impervious ice barrier layer is partly supported by the force applied to its lower surface as a result of the pressure of the gas boiling-off from the liquefied gas. The weight of the layer may be varied by adding water to freeze to the layer, or removing ice from the layer so that gases may be stored at any one of a wide range of pressures without over-stressing the supporting structure for the impervious icebarrier layer.

I claim:

1. A liquefied gas container, comprising:

wall means including a substantially vertically extending sidewall means defining an enclosure for storing a liquefied gas and having an opening at the upper end thereof;

receptacle means capable of holding a body of liquid extending across said opening for substantially closing same, said receptacle means containing therein a layer of frozen material which is flowable at normal ambient temperatures and which is frozen at the storage temperatures for the liquefied gas, said layer of frozen material extending over substantially the whole of said opening;

support means connected to said receptacle means for maintaining said receptacle means and said layer of frozen material positioned across said opening in substantially stationary relationship relative to said wall means; and

seal means coacting between said wall means and said receptacle means for creating a gastight seal around said receptacle means to isolate said enclosure from the region above said receptacle means whereby said frozen material and said receptacle means together oppose the upward pressure exerted thereon by the gas vapors contained in said enclosure. 2. A liquefied gas container according to claim 1, wherein said seal means comprises a seal member of gas'impervious sheet material having a portion thereof extending into said frozen material and a further portion thereof disposed in sealing relationship with said container sidewall means.

3. A liquefied gas container according to claim 1, further including gas-impervious cover means disposed over said opening for closing same, said cover means being disposed externally of said receptacle means and being spaced therefrom to define a substantially closed space therebetween; and

sealing means coacting between said sidewall means and the periphery of said cover means for forming a gastight seal therebetween so that said space as formed between said cover means and said receptacle means is substantially gastight, whereby the frozen material as contained in said receptacle means is thus isolated from both the liquefied gas contained in the enclosure and from the atmosphere disposed externally of said cover means.

4. A liquefied gas container according to claim 3, wherein the upper end of said sidewall means includes a recess area containing a liquid capable of freezing solid when subjected to the temperature of the liquefied gas stored within said container;

said seal means including a ringlike sheet of gas impervious material having the outer edge thereof disposed within the frozen material in said recess area, and the inner edge of said sheet of material extending into the layer of frozen material contained in said receptacle means; and

said sealing means including a further ringlike sheet of gasimpervious material having one edge thereof disposed within the frozen material contained in said recess area and the other edge thereof sealing secured to said cover means adjacent the periphery thereof.

5. A liquefied gas container according to claim 3, wherein said support means includes:

a frame structure supported on the upper end of said sidewall, said frame structure carrying said cover means; and

suspending means attached to said receptacle means and said frame structure, whereby said frame structure supports said receptacle means in suspension.

6. A liquefied gas container according to claim 3, wherein said sealing means includes a sheet of gas-impervious material disposed around the external surface of said opening, and wherein the peripheral portion of said cover means extends outwards beyond said external surface of said opening, said sheet being engaged with said external surface of said opening and extending from said external surface to said cover means whereby a gastight seal is provided.

7. A liquefied gas container according to claim 2, including:

means defining a recess in the upper end of said sidewall means, said seal member extending into said recess, and said recess containing a liquid capable of freezing solid when subjected to the temperature of liquid to be stored in said container, to provide a gastight seal preventing access of gas to the region above said cover means.

8. A liquefied gas container according to claim 7, wherein the liquid to be frozen in said recess is water and the frozen material in said receptacle means is ice.

9. A liquefied gas container according to claim 8, wherein said recess contains a mixture of sand and water.

10. A liquefied gas container according to claim 3, wherein said gastight space between said cover means and said receptacle means is filled with an inert gas at a pressure at least equal to atmospheric pressure. 

1. A liquified gas container, comprising: wall means including a substantially vertically extending sidewall means defining an enclosure for storing a liquified gas and having an opening at the upper end thereof; receptacle means capable of holding a body of liquid extending across said opening for substantially closing same, said receptacle means containing therein a layer of frozen material which is flowable at normal ambient temperatures and which is frozen at the storage temperatures for the liquified gas, said layer of frozen material extending over substantially the whole of said opening; support means connected to said receptacle means for maintaining said receptacle means and said layer of frozen material positioned across said opening in substantially stationary relationship relative to said wall means; and seal means coacting between said wall means and said receptacle means for creating a gas-tight seal around said receptacle means to isolate said enclosure from the region above said receptacle means whereby said frozen material and said receptacle means together oppose the upward pressure exerted thereon by the gas vapors contained in said enclosure.
 2. A liquefied gas container according to claim 1, wherein said seal means comprises a seal member of gas-impervious sheet material having a portion thereof extending into said frozen material and a further portion thereof disposed in sealing relationship with said container sidewall means.
 3. A liquified gas container according to claim 1, further including gas-impervious cover means disposed over said opening for closing same, said cover means being disposed externally of said receptacle means and being spaced therefrom to define a substantially closed space therebetween; and sealing means coacting between said sidewall means and the periphery of said cover means for forming a gas-tight seal therebetween so that said space as formed between said cover means and said receptacle means is substantially gas-tight, whereby the frozen material as contained in said receptacle means is thus isolated from both the liquified gas contained in the enclosure and from the atmosphere disposed externally of said cover means.
 4. A liquefied gas container according to claim 3, wherein the upper end of said sidewall means includes a recess area containing a liquid capable of freezing solid when subjected to the temperature of the liquified gas stored within said container; said seal means including a ring-like sheet of gas impervious material having the outer edge thereof disposed within the frozen material in said recess area, and the inner edge of said sheet of material extending into the layer of frozen material contained in said receptacle means; and said sealing means including a further ring-like sheet of gas-impervious material having one edge thereof disposed within the frozen material contained in said recess area and the other edge thereof sealing secured to said cover means adjacent the periphery thereof.
 5. A liquified gas container according to claim 3, wherein said support means includes: a frame structure supported on the upper end of said sidewall, said frame structure carrying said cover means; and suspending means attached to said receptacle means and said frame structure, whereby said frame structure supports said receptacle means in suspension.
 6. A liquefied gas container according to claim 3, wherein said sealing means includes a sheet of gas-impervious material disposed around the external surface of said opening, and wherein the peripheral portion of said cover means extends outwards beyond said external surface of said opening, said sheet being engaged with said external surface of said opening and extending from said external surface to said cover means whereby a gas-tight seal is provided.
 7. A liquefied gas container according to claim 2, including: means defining a recess in the upper end of said sidewall means, said seal member extending into said recess, and said recess containing a liquid capable of freezing solid when subjected to the temperature of liquid to be stored in said container, to provide a gas-tight seal preventing access of gas to the region above said cover means.
 8. A liquified gas container according to claim 7, wherein the liquid to be frozen in said recess is water and the frozen material in said receptacle means is ice.
 9. A liquefied gas container according to claim 8, wherein said recess contains a mixture of sand and water.
 10. A liquified gas container according to claim 3, wherein said gas-tight space between said cover means and said receptacle means is filled with an inert gas at a pressure at least equal to atmospheric pressure. 